The present invention relates to a method of stabilizing a corrosion inhibitor in an acidizing treatment of a subterranean formation or well bore employing selected compounds which substantially reduce the potential for precipitate formation from the corrosion inhibitor upon acid spending of the acidic solution.
Acidizing and fracturing treatments using aqueous acidic solutions commonly are carried out in hydrocarbon-containing subterranean formations penetrated by a well bore to accomplish a number of purposes, one of which is to increase the permeability of the formation. The increase in formation permeability normally results in an increase in the recovery of hydrocarbons from the formation.
In acidizing treatments, aqueous acidic solutions are introduced into the subterranean formation under pressure so that the acidic solution flows into the pore spaces of the formation. The acidic solution reacts with acid-soluble materials contained in the formation which results in an increase in the size of the pore spaces and an increase in the permeability of the formation.
In fracture acidizing treatments, one or more fractures are produced in the formation and the acidic solution is introduced into the fracture to etch flow channels in the fracture face. The acid also enlarges the pore spaces in the fracture face and in the formation.
A problem associated with acidizing subterranean formations is the corrosion by the acidic solution of the tubular goods in the well bore and the other equipment used to carry out the treatment. The expense of repairing or replacing corrosion damaged equipment is extremely high. The corrosion problem is exacerbated by the elevated temperatures encountered in deeper formations.
Various methods have been proposed to decrease the corrosion problem related to acidizing treatments, however, the corrosion inhibitors employed generally are effective only at temperature levels below about 250.degree. F. It would be desirable to provide a composition and method for acid treating a subterranean formation which overcomes at least some of the corrosion problem resulting from contact of the aqueous acidic treating solutions with ferrous and other metals while preventing further problems caused by precipitation of various compounds from the acidic solutions upon acid spending.